This invention relates to electronic musical instruments which are controlled by a keyboard of the type used in pianos, organs, etc. The invention describes a method for achieving a touch sensitive response to key depressions as heard through the audio system of an electronic musical instrument.
Touch sensitive or touch responsive systems have existed in electronic musical instruments of the analog type for some years. Many such systems comprise a pair of contacts which are actuated by the keys of the keyboard to charge a capacitor. The resulting voltage of the capacitor is directly related to the speed at which a given key is depressed. The resulting voltage, which varies in relation to the speed of the depression of the key, is applied to a gating or similar device creating a periodic waveform for the control of the tone generators of the instrument. Other similar methods have been applied in electronic musical instruments of the digital type. In these instances a varying analog voltage, which may be obtained from an electromagnetic transducer or similar device, is converted into digital information and used to "scale" the amplitude values of the output digital waveform signal. Different arrangements and/or combinations of these systems have also been attempted over the years.
The above methods in either analog or digital tone reproduction systems of the electronic musical instruments in which they were used provided a stepped cyclic reproduction of the sound when heard through a standard audio amplification system. Additionally, digital-type electronic musical instruments are known to have positive attack associated with the keying of the instrument rather than a touch sensitive system for following oo exactly the depression and release of the keys. The positive attack feature requires the completion of the entire attack sequence and may require a certain number of steady state cycles.
It is therefore an object of the present invention to provide complete touch sensitivity to the keys of an electronic musical instrument, whether digital, analog or hybrid, to effect a more realistic response to the play of the instrument. This is accomplished by providing a varying amplitude response related to the speed and time duration at which the keys are played coupled with a non-positive attack function.
Other objects will appear hereinafter.